The gentlemen that stated the 240 has limited shock travel is actually correct, to an extent. They have enough travel with a stock spring, but really don't for a run of the mill lowering spring, as they are too low and too soft to do much of any good.
The stock 240 shock is just under 13" (shock housing itself). All of the Koni's that I put together are shorter than the OEM setup. Fromxter's are 12.5" iirc, and the Koni 86** are 11.75" What that means is that you are gaining back 1.25" of travel or almost 1/2 of what the car had originally. Obviously no one is going to rock the 4x4 look with an aftermarket setup, but it allows you to maintain sufficient shaft travel and safely lower the car.
The Sentra by nature suffers from an almost indentical front end setup, from a limited travel point of view. On the Sentra we use a Maxima insert (which is what I'm currently running on my turbo B14). The Maxima insert installed in a housing is just a hair under 12" installed. This insert would work great for the 240 as well, but it requires that the shock be removed from the car (or at least the camber plate and spring removed) to be adjusted. To adjust you have to bottom out the shaft to the bottom of the shock and rotate counter clockwise (firm) and clockwise (soften) The Maxima insert will handle a 450 lb spring as well. (I have a 440 spring on mine currently)
Now I'm sure someone will bring up about having dual height adjustability offsets needing to lose "shock" travel because you don't have to use the spring perch for height adjustments. The issue isn't necessarily just stock travel, but I have not driven a JDM setup yet that had enough compression travel.
Dual height adjustability is a gimmick to allow cheap manufacturers the ability to sell the same shock over a spread of vehicles. 99% of the time, the shock is not revalved for different vehicles, like most assume, and it is just slapped from one to the next. The damping for most JDM/Taiwanese setups don't have a broad enough curve to handle different spring rates (not mention what they do have is not remotely ideal either). Have you ever wondered why almost every JDM setup comes with the same spring rates...even for different chassis? Most don't even care if it is multi link, mac, or double wishbone setups.
Some pictures of the various setups to help visualize how things are setup:
OEM based setup (Maxima insert)
Unfinished housing w/o flange installed:
8611/8610 Housing
How low my Sentra currently sits:
